The present invention relates, in general, to sealing devices and, more particularly, this invention relates to a positive stop means for use in combination with an annular type sealing device and still, more particularly, the instant invention relates to an improved annular type sealing device having a positive stop means for use in at least one predetermined type valve member.
As is generally well known in the fluid pressure art, various types of sealing devices have been in widespread use for a number of years. These sealing known sealing devices include annular type sealing devices which are used in valve members extensively to control the flow of fluids. Such sealing devices include both metal to metal type seals and flexible elastomeric type seals.
An example of a prior art valve equipped with a metal to metal type sealing means is taught in U.S. Pat. No. 5,145,150.
The flexible elastomeric type seals will generally take the form of an elastomer O-ring or a generally flat type sealing member. The generally flat type sealing members are usually of two distinct types. A first type being a substantially flat surface over the entire face of the sealing member. A second type includes an annular raised portion being disposed on the generally flat surface of the sealing member.
An example of a prior art annular type sealing device having a relatively flat surface is taught in U.S. Pat. No. 5,647,398.
During use, these sealing members can be subjected periodically to some rather severe operating pressures. These relatively severe operating pressures can and usually does cause detrimental premature wear on the sealing members. Obviously, such premature wear is an added cost for the user. Such added cost is due to both the cost of the sealing member itself and the labor cost that is associated with replacing the sealing member due to premature wear. Even more importantly is the down time that can be experienced on the equipment using such sealing members.
Of even more concern, however, is the fact that some valves may be employed in a critical use application and, in this application, if a seal should fail there could be catastrophic results. Some such critical use applications, for example, could be a brake valve used on a railway locomotive, or railway car, brake valve.
According to a first aspect, the present invention provides an annular sealing device having a positive stop. Such positive stop preventing over pressurization occurring on the sealing device. The annular sealing device includes a substantially rigid support member having at least one substantially flat outer surface portion. A generally round cavity is formed in a substantially rigid support member adjacent the at least one substantially flat outer surface. This generally round cavity has a first predetermined diameter and a predetermined depth. A generally round elastomeric sealing member having a predetermined thickness and at a second predetermined diameter is disposed in the generally round cavity formed in such substantially rigid support member. The elastomeric sealing member has a substantially flat face engage a bowl with a predetermined surface to be sealed. A stop means is incapable with at least a portion of such substantially flat outer surface portion of the substantially rigid support member for preventing undue penetration of the surface to be sealed into the generally round elastomeric sealing member.
According to a second aspect, the present invention provides an annular sealing device having a positive stop to prevent over pressurization on the annular sealing device. The annular sealing device comprises a substantially rigid support member having at least one substantially flat outer surface portion. A generally round cavity is formed in the substantially rigid support adjacent the at least one substantially flat outer surface. Such generally round cavity has a first predetermined diameter and a predetermined depth. There is a generally round elastomeric sealing member having a predetermined thickness and a second predetermined diameter disposed in the generally round cavity formed in such substantially rigid support member. The generally round elastomeric sealing member has a substantially flat face portion. An annular raised portion is disposed on the substantially flat face portion of the generally round elastomeric sealing member. This annular raised portion is engageable with a surface to be sealed. There is a stop means engageable with at least a portion of the substantially flat outer surface portion of the substantially rigid support member which prevents undue pressure on the annular raised portion of the general round elastomeric sealing member during use.
According to a third and final aspect, the present invention provides a valve device having improved sealing characteristics. Such valve device includes a valve body portion having a longitudinal bore formed therein and wrench engaging portion disposed on an outer surface thereof. A valve stem is disposed for longitudinal movement within such longitudinal bore formed in the valve body portion. Such valve stem having a substantially rigid flat bottom surface portion. There is a generally round cavity formed in the valve stem adjacent the substantially rigid flat bottom surface portion. This generally round cavity has a first predetermined diameter and a predetermined depth. A generally round elastomeric sealing member having a predetermined thickness and a second predetermined diameter is disposed in the generally round cavity formed in such valve stem adjacent the substantially rigid flat bottom surface portion. This generally round elastomeric sealing member has at least one of a substantially flat face engageable with a surface to be sealed and an annular raised portion disposed on the substantially flat face and engageable with a surface to be sealed. A stop means is engageable with at least a portion of the substantially flat rigid bottom surface portion of the valve stem for preventing undue pressure on the generally round elastomeric sealing member. A coil spring is disposed around a predetermined portion of the valve stem and a locking nut is threadedly engageable with an outer surface of such body adjacent one end thereof. Finally there is an adjusting nut threadedly engageable with the outer surface of the valve body adjacent such one end thereof.
It is, therefore, one of the primary objects of the present invention to provide an improved sealing member having a positive stop means which will thereby exhibit an extended life when compared to existing sealing members.
A further primary object of the present invention is to provide a valve device which will substantially prevent increased pressurization of fluid within a pressure vessel beyond the set point of the valve device.
Another object of the present invention is to provide an improved sealing member having a positive stop means which will be relatively inexpensive to manufacture when compared to prior art type sealing members.
Still another object of the present invention is to provide an improved sealing member having a positive stop means which can be interchangeable with existing sealing members without costly modifications.
Yet another object of the present invention is to provide an improved sealing member having a positive stop means which can withstand increased pressures when compared to existing sealing members.
An additional object of the present invention is to provide an improved sealing member having a positive stop means for use in a railway brake system which will increase the reliability of such brake system.
A further object of the present invention is to provide an improved sealing member having a positive stop means which when used in a valve member allows a very repeatable set point for such valve.
Still yet another object of the present invention is to provide an improved sealing member having a positive stop means in which such sealing member can be molded in place in a cavity formed in a valve stem thereby essentially eliminating the need for critical machining of the valve stem.
It is an additional object of the present invention to provide an improved sealing member having a positive stop means which will be more reliable in service.
In addition to the various objects and advantages of the present invention which have been described above, various other objects and advantages of the instant invention will become more readily apparent to those persons who are skilled in the relevant art from the following more detailed description of the invention, particularly, when such detailed description is taken in conjunction with the attached drawing Figures and with the appended claims.